1. Field of the Invention
The present invention relates to hydraulic couplings used in undersea drilling and production applications and seals used in those couplings. More particularly, the invention involves an annular seal that is restrained from radial movement into the bore of the female member by a dovetail interfit with a two-piece retainer.
2. Description of the Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male and a female member with soft seals positioned within the female member to seal the junction between the male and female members.
The female member is generally a cylindrical body with a relatively large diameter longitudinal bore at one end and a relatively small diameter longitudinal bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore contains soft seals and receives the male portion of the coupling. The male member includes a cylindrical portion or probe at one end having a diameter approximately equal to the diameter of the large bore in the female portion of the coupling. The male member also includes a connection at its other end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to the various embodiments of the device, the soft seals, resembling O-rings, either abut the end or face of the male member or engage the cylindrical probe wall about its circumference. The hydraulic fluid is then free to flow through the female and male portions of the coupling, and the seals prevent that flow from escaping about the joint and the coupling.
In some instances, a check valve may be installed in the female member and also in the male member. Each check valve opens when the coupling is made up and closes when the coupling is broken so as to prevent fluid from leaking out of the system of which the coupling is a part.
In U.S. Pat. No. 4,694,859 to Robert E. Smith, III, an undersea hydraulic coupling and metal seal is disclosed. This patent provides a reusable metal seal which engages the circumference of the probe and is positioned within the female member body. The metal seal is held in place by a cylindrical body or retainer. A clip holds the retainer within the body, preventing escape of the retainer or metal seal from the body. When the male and female portions of the coupling are parted under pressure, the retainer prevents the metal seal from blowing out through the bore of the female member.
U.S. Pat. No. 4,694,859 also discloses a soft annular seal or O-ring at the inner cylindrical surface of the retainer, which engages the probe circumference. The soft annular seal generally is used as a secondary seal, and prevents escape of fluid should the metal seal fail. As the probe begins to enter the retainer bore, it begins to engage a soft annular seal intermediate the retainer bore. This contact compresses the seal and creates a sliding seal between it and the probe wall. The annular seal or soft seal is of a relatively pliable material, for example, rubber or synthetic elastomer. The annular seal is generally ring-shaped and is located in a sealed groove.
A problem has been encountered with the soft annular seal intermediate the retainer. When the male member or probe is removed from the female member under high ambient seawater pressure, the soft annular seal oftentimes will blow out of the female member and be lost. There is no mechanism for retention of the soft annular seal in the female section.
The implosion of the soft seal is a characteristic problem in the prior art. As the male member or probe is pulled out of the female member bore, the leading face of the male member reaches the soft annular seal intermediate that bore. When the face crosses the midpoint of the soft annular seal, there is nothing to restrain the seal from radial movement into the bore. The very low pressure or vacuum in the bore results in the seal being imploded into the bore, as the ambient seawater begins to enter the bore at high pressure.
When the soft annular seal blows out through the female bore, it may be extremely difficult to replace the seal within the bore. There are also difficulties encountered in machining a groove in the female bore for the seal and inserting the seal in that groove.
The problem of blowing out or implosion of the soft annular seal and difficulties of manufacturing, assembly or reassembly are solved by the present invention.